/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright 2003-2007 Jive Software.
 *
 * All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jivesoftware.smackx.packet;

import org.jivesoftware.smack.Roster;
import org.jivesoftware.smack.RosterEntry;
import org.jivesoftware.smack.RosterGroup;
import org.jivesoftware.smack.packet.PacketExtension;
import org.jivesoftware.smackx.RemoteRosterEntry;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 * Represents XMPP Roster Item Exchange packets.
 * <p>
 * 
 * The 'jabber:x:roster' namespace (which is not to be confused with the
 * 'jabber:iq:roster' namespace) is used to send roster items from one client to
 * another. A roster item is sent by adding to the &lt;message/&gt; element an
 * &lt;x/&gt; child scoped by the 'jabber:x:roster' namespace. This &lt;x/&gt;
 * element may contain one or more &lt;item/&gt; children (one for each roster
 * item to be sent).
 * <p>
 * 
 * Each &lt;item/&gt; element may possess the following attributes:
 * <p>
 * 
 * &lt;jid/&gt; -- The id of the contact being sent. This attribute is required.
 * <br>
 * &lt;name/&gt; -- A natural-language nickname for the contact. This attribute
 * is optional.
 * <p>
 * 
 * Each &lt;item/&gt; element may also contain one or more &lt;group/&gt;
 * children specifying the natural-language name of a user-specified group, for
 * the purpose of categorizing this contact into one or more roster groups.
 * 
 * @author Gaston Dombiak
 */
public class RosterExchange implements PacketExtension {

	private List remoteRosterEntries = new ArrayList();

	/**
	 * Creates a new empty roster exchange package.
	 * 
	 */
	public RosterExchange() {
		super();
	}

	/**
	 * Creates a new roster exchange package with the entries specified in
	 * roster.
	 * 
	 * @param roster
	 *            the roster to send to other XMPP entity.
	 */
	public RosterExchange(Roster roster) {
		// Add all the roster entries to the new RosterExchange
		for (RosterEntry rosterEntry : roster.getEntries()) {
			this.addRosterEntry(rosterEntry);
		}
	}

	/**
	 * Adds a roster entry to the packet.
	 * 
	 * @param rosterEntry
	 *            a roster entry to add.
	 */
	public void addRosterEntry(RosterEntry rosterEntry) {
		// Obtain a String[] from the roster entry groups name
		List<String> groupNamesList = new ArrayList<String>();
		String[] groupNames;
		for (RosterGroup group : rosterEntry.getGroups()) {
			groupNamesList.add(group.getName());
		}
		groupNames = groupNamesList.toArray(new String[groupNamesList.size()]);

		// Create a new Entry based on the rosterEntry and add it to the packet
		RemoteRosterEntry remoteRosterEntry = new RemoteRosterEntry(
				rosterEntry.getUser(), rosterEntry.getName(), groupNames);

		addRosterEntry(remoteRosterEntry);
	}

	/**
	 * Adds a remote roster entry to the packet.
	 * 
	 * @param remoteRosterEntry
	 *            a remote roster entry to add.
	 */
	public void addRosterEntry(RemoteRosterEntry remoteRosterEntry) {
		synchronized (remoteRosterEntries) {
			remoteRosterEntries.add(remoteRosterEntry);
		}
	}

	/**
	 * Returns the XML element name of the extension sub-packet root element.
	 * Always returns "x"
	 * 
	 * @return the XML element name of the packet extension.
	 */
	public String getElementName() {
		return "x";
	}

	/**
	 * Returns the XML namespace of the extension sub-packet root element.
	 * According the specification the namespace is always "jabber:x:roster"
	 * (which is not to be confused with the 'jabber:iq:roster' namespace
	 * 
	 * @return the XML namespace of the packet extension.
	 */
	public String getNamespace() {
		return "jabber:x:roster";
	}

	/**
	 * Returns an Iterator for the roster entries in the packet.
	 * 
	 * @return an Iterator for the roster entries in the packet.
	 */
	public Iterator getRosterEntries() {
		synchronized (remoteRosterEntries) {
			List entries = Collections.unmodifiableList(new ArrayList(
					remoteRosterEntries));
			return entries.iterator();
		}
	}

	/**
	 * Returns a count of the entries in the roster exchange.
	 * 
	 * @return the number of entries in the roster exchange.
	 */
	public int getEntryCount() {
		return remoteRosterEntries.size();
	}

	/**
	 * Returns the XML representation of a Roster Item Exchange according the
	 * specification.
	 * 
	 * Usually the XML representation will be inside of a Message XML
	 * representation like in the following example:
	 * 
	 * <pre>
	 * &lt;message id="MlIpV-4" to="gato1@gato.home" from="gato3@gato.home/Smack"&gt;
	 *     &lt;subject&gt;Any subject you want&lt;/subject&gt;
	 *     &lt;body&gt;This message contains roster items.&lt;/body&gt;
	 *     &lt;x xmlns="jabber:x:roster"&gt;
	 *         &lt;item jid="gato1@gato.home"/&gt;
	 *         &lt;item jid="gato2@gato.home"/&gt;
	 *     &lt;/x&gt;
	 * &lt;/message&gt;
	 * </pre>
	 * 
	 */
	public String toXML() {
		StringBuilder buf = new StringBuilder();
		buf.append("<").append(getElementName()).append(" xmlns=\"")
				.append(getNamespace()).append("\">");
		// Loop through all roster entries and append them to the string buffer
		for (Iterator i = getRosterEntries(); i.hasNext();) {
			RemoteRosterEntry remoteRosterEntry = (RemoteRosterEntry) i.next();
			buf.append(remoteRosterEntry.toXML());
		}
		buf.append("</").append(getElementName()).append(">");
		return buf.toString();
	}

}
